Thr Levels Research Articles

Threonine modulates immune response, antioxidant status and gene expressions of antioxidant enzymes and antioxidant-immune-cytokine-related signaling molecules in juvenile blunt snout bream (Megalobrama amblycephala).

A 9-week feeding trial was conducted to investigate the effects of graded dietary threonine (Thr) levels (0.58-2.58%) on the hematological parameters, immune response, antioxidant status and hepatopancreatic gene expression of antioxidant enzymes and antioxidant-immune-cytokine-related signaling molecules in juvenile blunt snout bream. For this purpose, 3 tanks were randomly arranged and assigned to each experimental diet. Fish were fed with their respective diet to apparent satiation 4 times daily. The results indicated that white blood cell, red blood cell and haemoglobin significantly responded to graded dietary Thr levels, while hematocrit didn't. Complement components (C3 and C4), total iron-binding capacity (TIBC), immunoglobulin M (IgM), superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase (CAT) increased with increasing dietary Thr levels up to 1.58-2.08% and thereafter tended to decrease. Dietary Thr regulated the gene expressions of Cu/Zn-SOD, Mn-SOD and CAT, GPx1, glutathione S-transferase mu (GST), nuclear factor erythroid 2-related factor 2 (Nrf2), heat shock protein-70 (Hsp70), tumor necrosis factor-alpha (TNF-α), apolipoprotein A-I (ApoA1), glyceraldehyde 3-phosphate dehydrogenase (GAPDH) and fructose-bisphosphate aldolase B (ALDOB); while the gene expression of peroxiredoxin II (PrxII) was not significantly modified by graded Thr levels. These genes are involved in different functions including antioxidant, immune, and defense responses, energy metabolism and protein synthesis. Therefore, this study could provide a new molecular tool for studies in fish immunonutrition and shed light on the regulatory mechanisms that dietary Thr improved the antioxidant and immune capacities of fish.

Lysine, methionine, phenylalanine, arginine, valine, isoleucine, leucine, and threonine maintenance requirements of broiler breeders

Five hundred and sixty Cobb-Vantress broiler breeders were used to determine the maintenance requirement of dietary Arg, His, Ile, Leu, Lys, Met, Phe, Thr, and Val in 10 21-d assays using the comparative slaughter technique. Fifty sexually immature broiler breeder pullets per assay were given crystalline amino acid diets containing graded levels of Arg, His, Ile, Leu, Lys, Met, Phe, Thr, or Val, respectively, representing 0, 10, 20, 30, 40% of their suggested requirement level (NRC, 1994) with all other amino acids maintained at 40% of their suggested requirement level. Sixty hens were slaughtered prior to the beginning of the study to assess initial body composition at 3 weight groups. Linear regression lines (protein accretion vs. amino acid intake) were determined and the maintenance requirements were calculated based on zero protein accretion. The maintenance requirements expressed on a metabolic weight basis were determined to be 174, 94, 52, 81, 60, 126, 133, and 155 mg/kg0.75/d for Arg, Ile, Leu, Lys, Met, Phe, Thr, and Val, respectively. Additionally, the maintenance requirements, expressed on metabolic protein weight basis, were determined to be 651, 329, 172, 295, 223, 523, 478, and 546 mg/kgCP/d for Arg, Ile, Leu, Lys, Met, Phe, Thr, and Val, respectively. The requirement for His could not be established as the results obtained were outside of assay range.

Threonine affects digestion capacity and hepatopancreatic gene expression of juvenile blunt snout bream (Megalobrama amblycephala).

The present study conducted a 9-week feeding trial to investigate the effects of threonine (Thr) on the digestion capacity and hepatopancreas gene expression of juvenile blunt snout bream (Megalobrama amblycephala). For this purpose, three tanks (300 litres/tank) were randomly arranged and assigned to each experimental diet. Juvenile fish were fed with diets containing graded Thr levels (0·58, 1·08, 1·58, 2·08 or 2·58 % of the diet) to apparent satiation four times daily. At the end of the feeding trial, the results indicated that hepatopancreas weight, hepatosomatic index, hepatopancreatic protein content, intestinal weight, intestosomatic index and intestinal protein content increased with increasing dietary Thr levels up to 1·58 % and thereafter decreased (P< 0·05). The activities of chymotrypsin, trypsin, amylase and lipase elevated as dietary Thr levels increased up to 1·58 % (P< 0·05), while these activities decreased in most cases after 1·58 % dietary Thr except for chymotrypsin and trypsin in the hepatopancreas (plateau 1·58-2·08 % Thr). The relative gene expression levels of chymotrypsin, trypsin, amylase, lipase, target of rapamycin and insulin-like growth factor-I were up-regulated, and the highest values were observed with 1·58 % dietary Thr or 1·58 and 2·08 % dietary Thr, whereas the relative gene expression levels of eukaryotic translation initiation factor 4E-binding protein 2 gradually decreased (P< 0·10) as dietary Thr levels increased up to 1·58 % and thereafter significantly increased (P< 0·05), which could explain that about 1·58 % dietary Thr could improve the growth and development of digestive organs and activities of digestive enzymes of juvenile blunt snout bream.

Effects of acidified drinking water on performance, carcass, immune response, jejunum morphology, and microbiota activity of broiler chickens fed diets containing graded levels of threonine

A 2×4 factorial arrangement of treatments was used to investigate the effects of 2 levels of an acidifier supplement (0 or 350mL/1000L) in drinking water on growth performance, carcass, immune response, intestinal microbial flora, and jejunum morphology of broiler chickens fed diets based on 4 levels of dietary Thr (100, 110, 120, and 130% of the requirements). A total of 320 broiler chickens were assigned to 8 treatments with 4 replicate pens of 10 broiler chickens per pen. Growth performance traits, including daily weight gain, feed intake, and feed conversion ratio (FCR), were recorded. The broiler chickens immunized against Newcastle disease virus (NDV) at 8d of age. Blood samples were drawn from the wing vein 7 and 14d after vaccination for the determination of primary and secondary antibody responses. In addition, blood samples were collected in tubes containing anticoagulant to determine the number of heterophil (H) and lymphocyte (L). At the end of the experiment, 4 broiler chickens per treatment were selected and killed, and, then, the relative weights of carcass parts, jejunum morphology, and intestinal microbial population were determined. The results showed that broiler chickens received acidified drinking water (ADW) had greater (P<0.05) feed intake (28.51 vs. 27.30g/chicken/d) and weight gain (20.01 vs. 19.26g/chicken/d) than those received without water additive during the starter period. Neither Thr nor ADW had any effect on any carcass traits of broiler chickens. Heterophil count and H to L ratio were increased (35.87 and 0.63%, respectively) and lymphocyte count was decreased (56.50%) in broiler chickens fed diets containing 110% threonine (P<0.05). However, antibody titer against NDV was not influenced by experimental treatments. In the jejunum, the villus width (136.8µm) and crypt depth (188.9µm) were greater and the ratio of VH to CD was lower (6.50) in broiler chickens received ADW (P<0.05). Moreover, the population of Escherichia coli decreased (5.79 vs. 6.23log10 cfu/g) in broiler chickens received ADW, while lactobacilli population increased (7.45 vs. 6.90log10 cfu/g; P<0.05). However, dietary Thr had no effect on jejunum morphology and intestinal microbial population of broiler chickens. The present findings indicate that ADW improves growth performance (0–10d), jejunum morphology, and intestinal lactobacilli population of broiler chickens. In addition, the use of 110% Thr increased H to L ratio in broiler chickens. However, different graded concentrations of Thr did not alter growth performance, intestinal morphology, and microbiota activity.

Effects of Dietary Threonine Levels and Stocking Density on the Performance, Metabolic Status and Immunity of Broiler Chickens

ABSTRACT A total of 240 Cobb 500 broiler chic ks, 18 days old, were allocated to 10 treatments groups, eachof which included 4 replicates. Experimental treatments consisted of a 5×2 factorial arrangementwith 5 levels of L-threonine (Thr) supplementation and 2 levels of stocking density (11.90 birds m G 2 as the normal stocking density or 16.66 birds mG 2 as the high stocking density). L-Thr was addedto a basal diet at 0.0 (control group), 0.25, 0.50, 0.75 and 1.00 g kgG 1 diet. Dietary Thr values were0.69, 0.71 (deficient), 0.74 (adequate; 100% NRC), 0.76 and 0. 79% (excess) of the current NRCrecommendations. At 42 days of age, dietary Thr levels had no significant effect on performance,immunity, plasma total protein and glucose (GLU). However, plasma cholesterol (CHO) levelsdecreased significantly (p<0.05) with L-Thr supplementation and the lowest value occurred at0.74% total dietary Thr. In addition, plasma triio dothyronine (T3) and thyroxine (T4) levels werehigher (p<0.05) at 0.76% total dietary Thr comp ared with the control group. The normal stockingdensity resulted in better performance (p<0.05) co mpared with the high stocking density. However,stocking density did not affect plasma total protein, total Ig, IgG, IgM, total lipids, GLU, CHO, T3and T4 levels. Interactions between Thr level and stocking density were observed for plasmalevels of total lipids and cholesterol. In conclusion, total dietary Thr level at 0.69% (93% of NRCrecommendations) is sufficient to improve broiler performance or immunity under high stockingdensity. However, 0.74% total dietary Thr level has a positive effect on decreasing plasma totallipids and cholesterol levels during growing-finishing phase.

The optimal lysine and threonine intake for Cobb broiler breeder hens using Reading model

This study aimed to determine the optimal intake of lysine and threonine for broiler breeder hens. Two experiments were conducted to evaluate the responses of birds to digestible lysine (Lys) and threonine (Thr). Eight treatments were assessed in both experiments, with six replicates of eight birds in the Lys experiment and ten birds in the Thr experiment. The dietary levels of Lys and Thr were obtained by a dilution technique. The experimental period was ten weeks for each amino acid studied, which included six weeks of adaptation and four weeks of data collection. The amino acid intake, egg mass and body weight were adjusted using a Reading model. Based on the model coefficients, the cost of the synthetic amino acids sources and the price of fertile eggs determined the intake of each amino acid to maximize. The minimum intake of Lys and Thr reduced egg production by 40 and 30%, respectively, the weight of the eggs decreased by 12 and 9% with the same intake of Lys and Thr, respectively. The models generated by predicting Lys and Thr intake were as follows: Lys=11×E+31×W and Thr=9.5×E+32×W, where E=egg mass, g/bird per day, and W=body weight, kg/bird. Based on the models, 3kg birds with an egg mass production of 50g/day require 643mg/bird per day of Lys and 569mg/bird per day of Thr. The optimum economic intake was calculated at 954 and 834mg/bird per day for Lys and Thr, respectively, reflecting a dietary concentration of 0.636% Lys and 0.556% Thr for a feed intake of 150g/bird per day.

Phosphorylation and Inactivation of Glycogen Synthase Kinase 3β (GSK3β) by Dual-specificity Tyrosine Phosphorylation-regulated Kinase 1A (Dyrk1A)

Glycogen synthase kinase 3β (GSK3β) participates in many cellular processes, and its dysregulation has been implicated in a wide range of diseases such as obesity, type 2 diabetes, cancer, and Alzheimer disease. Inactivation of GSK3β by phosphorylation at specific residues is a primary mechanism by which this constitutively active kinase is controlled. However, the regulatory mechanism of GSK3β is not fully understood. Dual-specificity tyrosine phosphorylation-regulated kinase 1A (Dyrk1A) has multiple biological functions that occur as the result of phosphorylation of diverse proteins that are involved in metabolism, synaptic function, and neurodegeneration. Here we show that GSK3β directly interacts with and is phosphorylated by Dyrk1A. Dyrk1A-mediated phosphorylation at the Thr(356) residue inhibits GSK3β activity. Dyrk1A transgenic (TG) mice are lean and resistant to diet-induced obesity because of reduced fat mass, which shows an inverse correlation with the effect of GSK3β on obesity. This result suggests a potential in vivo association between GSK3β and Dyrk1A regarding the mechanism underlying obesity. The level of Thr(P)(356)-GSK3β was higher in the white adipose tissue of Dyrk1A TG mice compared with control mice. GSK3β activity was differentially regulated by phosphorylation at different sites in adipose tissue depending on the type of diet the mice were fed. Furthermore, overexpression of Dyrk1A suppressed the expression of adipogenic proteins, including peroxisome proliferator-activated receptor γ, in 3T3-L1 cells and in young Dyrk1A TG mice fed a chow diet. Taken together, these results reveal a novel regulatory mechanism for GSK3β activity and indicate that overexpression of Dyrk1A may contribute to the obesity-resistant phenotype through phosphorylation and inactivation of GSK3β.

Effect of excess dietary threonine on laying performance, egg quality, serum free amino acids, and digestive enzymes activities of laying hens during the postpeak period

A total of 640 layer hens, 56 wk of age, were allocated to 4 dietary treatments groups, each of which included 5 replicates of 32 hens. Graded levels ofl-Thr were added to the basal diet at 0.0 (control), 1.0, 2.0, and 3.0 g/kg; determined Thr values were 5.7, 6.5, 7.4, and 8.7 g/kg of diet, respectively. In the 53-d feeding trial, egg production increased significantly due to dietaryl-Thr supplementation. Hens fed 2.0 g of Thr/kg of diet had significantly higher egg production than the control diet. Supplementing the diet withl-Thr did not affect egg weight or feed intake, but egg mass increased significantly. Also, FCR was improved significantly and the best FCR was exhibited by hens receiving 2.0 g of Thr/kg of diet. Feeding laying hens a diet containing 2.0 g ofl-Thr/kg of diet improved Haugh units linearly; however, egg shell thickness decreased linearly as the level of dietary Thr increased, and the lowest value was observed for hens fed 3.0 g of Thr/kg of diet. Serum free Thr increased linearly as supplemental Thr increased, but serum free Ile, Phe, and Tyr decreased. No differences attributable tol-Thr were found among groups in the activity of digestive enzymes (trypsin and amylase) in the mucosal homogenates of the jejunum. The activity of α-alkaline phosphatase in the jejunum was analyzed as a marker of mucosal enterocyte maturation and no differences due tol-Thr supplementation were noted. In conclusion, feeding laying hens from 56 to 64 wk of agel-Thr up to 2.0 g/kg can improve laying performance and Haugh units.

Nutritional requirement of digestible threonine for white egg layers of 60 to 76 weeks of age

The objective of this study was to determine the requirement for digestible Thr for optimum performance of white egg layers in the period from 60 to 76 wk of age. DeKalb White Leghorn layers with an average weight of 1,345 kg were distributed 5 increasing levels of digestible Thr (0.523, 0.546, 0.569, 0.592, and 0.615%) in a completely randomized design, with 6 replicates and 6 birds per experimental unit for a total of 180 birds. The dietary treatments contained 0.759% of digestible Lys, which was obtained using the prediction equation of the Brazilian Tables for Poultry and Swine, and each treatment consisted of a digestible Thr-to-Lys ratio of 69, 72, 75, 78, or 81%. The digestible Thr levels had a linear effect on feed intake and a quadratic effect on egg production, egg mass, and feed conversion per mass and per dozen eggs. In conclusion, a digestible Thr-to-Lys ratio of 75.14% is recommended for White Leghorn of 60 to 76 wk of age, corresponding to the level of 0.570% in the diet and a daily intake of digestible Thr of 622 mg/bird.

Estimation of the standardized ileal digestible lysine requirement and the ideal ratio of threonine to lysine for late finishing gilts fed low crude protein diets supplemented with crystalline amino acids

Two experiments were conducted to investigate the effects of various standard ileal digestible (SID) lysine (Lys) levels and SID threonine (Thr) to Lys ratios on the performance and carcass characteristics of finishing gilts receiving low crude protein (CP) diets supplemented with crystalline amino acids (CAA). In Exp. 1, 108 gilts (87.8±5.9kg) were randomly allotted to one of six diets which consisted of a high CP (135g/kg) diet with 6.1g/kg SID Lys or five low CP (100g/kg) diets providing SID Lys levels of 4.9, 5.5, 6.1, 6.7 and 7.3g/kg, respectively. Gilts were housed in three pigs per pen with six pens per treatment. At the end of the 28 days experiment, 36 gilts (one pig per pen) with average body weight (BW) of 116kg were killed to evaluate carcass traits. The SID Lys levels required to maximize average daily gain (ADG) and optimize feed conversion ratio (FCR) as well as to minimize serum urea nitrogen (SUN) levels were 5.7, 5.8 and 6.1g/kg using a linear-break point model and 6.5, 6.5 and 6.6g/kg using a quadratic model. The fat-free lean gain tended to increase linearly with the increase in dietary SID Lys levels from 4.9 to 7.3g/kg when gilts receiving a low CP diet (linear effect, P=0.06). In Exp. 2, 90 gilts (90.6±5.7kg) were utilized in another dose–response study. Based on the Lys requirement estimated in Exp. 1, dietary treatments were formulated to contain 5.1g/kg SID Lys to ensure the dietary Lys level was marginally deficient for late finishing gilts. Graded levels of crystalline Thr (0, 0.3, 0.6, 0.9 or 1.2g/kg) were added to the basal diet providing SID Thr to Lys ratios of 0.54, 0.60, 0.66, 0.72 or 0.78, respectively. Each diet was fed to six pens with three gilts per pen. At the end of Exp. 2, 30 gilts (one pig per pen) were slaughtered to evaluate carcass traits (average BW=118kg). The optimum SID Thr to Lys ratios to maximize ADG and FCR as well as to minimize SUN levels were 0.61, 0.63 and 0.64 using a linear-break point model and 0.70, 0.75 and 0.74 using a quadratic model. With the exception of L* light (linear effect, P<0.05), no effect on carcass characteristics was observed with increasing dietary SID Thr to Lys ratio.

Barley does not change threonine requirement in growing pigs fed a barley–casein-based diet compared to a casein-based diet, as determined by the indicator amino acid oxidation method

Ileal threonine (Thr) losses increase when young pigs are fed high fiber ingredients such as barley. Barley contains several anti-nutritive factors, e.g., insoluble fibers, which stimulate the secretion of intestinal mucin, a Thr-rich glycoprotein. We hypothesized that because the gut utilizes the majority of dietary Thr, primarily for mucin synthesis, an increase in mucin secretion and ileal losses of Thr will increase the whole body Thr requirement. The objective of this experiment was to compare the Thr requirement of pigs fed a barley–casein diet to a casein diet, using the indicator amino acid oxidation technique. Six barrows were fed diets containing 12% casein or 50% barley/6% casein at 50g/kg body weight/d. After a 7-d adaptation on the 0.35g Thr/kg body weight casein-based diet, pigs were fed casein diets with each of seven Thr levels (0.21–0.54g Thr/kg body weight in a random order) for 2-d with phenylalanine oxidation measured at the end of each period. After a 10-d adaptation to the barley-based diet, the same protocol was followed for barley-based diets with seven Thr levels in the same pigs. Using two-phase linear regression crossover analysis to determine breakpoints in individual pigs, the requirement on casein diet was 0.355±0.014g Thr/kg body weight/d, and 0.397±0.038g Thr/kg body weight/d on barley diets. Overall there was no difference (P>0.05) in Thr requirement between diets.

Phosphorylation of hypothalamic AMPK on serine(485/491) related to sustained weight loss by alpha-lipoic acid in mice treated with olanzapine.

Alpha-lipoic acid (ALA) was shown to suppress atypical antipsychotic drug (AAPD)-induced weight gain. However, its mode of action has remained unidentified. We aimed to identify mechanisms underlying anti-obesity effects of ALA in mice treated with olanzapine. We compared body weight and food intake among vehicle-, olanzapine-, and olanzapine plus ALA-treated mice, and measured hypothalamic AMP-activated protein kinase (AMPK) activity by detecting levels of Thr(172) and Ser(485/491) phosphorylation, which indicate activation and inhibition of AMPK, respectively. Body weights were increased by olanzapine in parallel with increased levels of Thr(172) phosphorylation of hypothalamic AMPK. Initially increased rate of weight gain was diminished as Thr(172) phosphorylation levels were decreased to control levels after 10days of olanzapine treatment. ALA successfully not only prevented olanzapine-induced weight gain but also induced additional weight loss even relative to control levels throughout the treatment period. During the initial stage, ALA's action was indicated by both suppression of olanzapine-induced Thr(172) phosphorylation and an increase in Ser(485/491) phosphorylation levels. However, in the later stage when no more increases in Thr(172) phosphorylation and weight gain by olanzapine were observed, ALA's action was only indicated by increased levels of Ser(485/491) phosphorylation. Our data suggest that anti-obesity effects of ALA may be related to modulation of both Ser(485/491) phosphorylation and Thr(172) phosphorylation of hypothalamic AMPK, while olanzapine-induced weight gain may be only associated with increase in Thr(172) phosphorylation. This might be an important mechanistic clue for thefuture development of anti-obesity drugs beyond control of AAPD-induced weight gain.

Ideal ratio of threonine to lysine in straight-run Cobb 500 broiler chickens from 15 to 28 d of age predicted from regression and broken-line models

Two bioassays were conducted to determine the ideal ratio of threonine (Thr) relative to lysine (Lys) in straight-run Cobb 500 broiler chickens from 15 to 28 d of age. Broiler chickens were fed wheat-corn gluten meal-based diet fortified with synthetic amino acids. A Lys-deficient basal diet was formulated to contain 0.60% standardised ileal digestible Lys (SID Lys) and subsequent treatments had 0.12% Lys added incrementally until a level of 1.2% SID Lys was reached for a total of six treatments. A Thr-deficient basal diet was formulated to contain 0.46% of standardised ileal digestible Thr (SID Thr) and subsequent treatments had 0.07% Thr added incrementally until a level of 0.81% SID Thr was reached for a total of six treatments. Both male and female birds were randomised across 48 floor pens (4 replicate pens, and 12 birds per pen) and fed one of the six levels of each of the test amino acid from 15 to 28 d of age. Body weight gain (BWG) and feed conversion ratio (FCR) responded quadratically (P < 0.0001) to graded levels of Thr (0.46–0.81%); however, these responses were linear (P < 0.0001) to different levels of Lys (0.60–1.20%). Using quadratic broken-line model, Lys requirements were estimated at 0.99 and 1.14% of diet for BWG and FCR, respectively. Lys requirements for BWG and FCR were estimated at 0.89 and 0.98% of diet with linear broken-line model. Thr requirement for BWG and FCR was estimated at 0.79 and 0.81% of diet with quadratic broken-line model, and 0.69 and 0.71% of diet with the linear broken-line model, respectively. Considering FCR as a response, the ideal ratios of SID Thr:SID Lys were 72 and 71% using the linear broken-line and quadratic broken line models, respectively.

Plasma free amino acid profiling of esophageal cancer using high-performance liquid chromatography spectroscopy.

To perform plasma free amino acid (PFAA) profiling of esophageal squamous cell carcinoma (ESCC) patients at different pathological stages and healthy subjects. Plasma samples from ESCC patients (n = 51) and healthy control adults (n = 60) were analyzed by high-performance liquid chromatography (HPLC). The ESCC patients included moderate/poorly-differentiation (n = 24), lymph node metastasis (n = 17) and clinical stage > Ib2 (n = 36). Partial least squares discriminant analysis was performed to demonstrate that the PFAA metabolic patterns enabled discrimination between ESCC patients and controls, and the Student t test was applied to assess significant differences in PFAA concentrations between the two groups. There were significant differences in the PFAA profiles between controls and ESCC patients. Compared with healthy controls, the levels of Asp, Glu, Gly, His, Thr, Tau, Ala, Met, Ile, Leu, and Phe were decreased in ESCC patients, but Cys was increased. There exists a strong correlation between PFAA profiles and clinicopathological characteristics in ESCC patients. The levels of many PFAAs (i.e., Glu, Asp, Ser, Gly, Tau, Ala, Tyr, Val, Ile, and Leu) were related to pathological grading, lymph node metastasis, and ESCC clinical stage. Very good discrimination between ESCC patients and control subjects was achieved by multivariate modeling of plasma profiles. HPLC-based plasma profiling analysis was shown to be an effective approach to differentiate between ESCC patients and controls. PFAA profiles may have potential value for screening or diagnosing ESCC.

Effects of dietary levels of glycine, threonine and protein on threonine efficiency and threonine dehydrogenase activity in hepatic mitochondria of chicks.

This study was carried out to evaluate the relationship between threonine (Thr) efficiency and Thr dehydrogenase (TDG) activity as an indicator of Thr oxidation on chicks fed with levels of diets (CP [17.5% and 21.5%] and Thr [3.8 and 4.7 g/100 g CP]; glycine [Gly][0.64% and 0.98%] and true digestible Thr [dThr] [0.45% and 0.60%]). Calculation of the Thr efficiency was based on N-balance data and an exponential N-utilization model, and TDG activity was determined as accumulation of aminoacetone and Gly during incubation of hepatic mitochondria. This study found that in the liver of chicks who received a diet containing up to 0.79% Thr (4.7 g Thr/100 g of CP) in the 17.5% CP diet, no significant (p>0.05) effect on TDG activity was observed. However, significantly (p = 0.014) increased TDG activity was observed with a diet containing 21.5% CP (4.7 g Thr/100 g of CP) and the efficiency of Thr utilization showed a significant (p = 0.001) decrease, indicating the end of the Thr limiting range. No significant (p>0.05) effect on the total TDG activity and accumulation of Gly was observed with addition of Gly to a diet containing 0.45% dThr. In addition, addition of Gly to a diet containing 0.60% dThr also did not result in a change in accumulation of Gly. Due to an increase in accumulation of aminoacetone, an elevated effect on total TDG activity was also observed. No significant (p>0.05) reduction in the efficiency of Thr utilization was observed after addition of Gly at the level of 0.45% dThr. However, significantly (p<0.001) reduced efficiency of Thr utilization was observed after addition of Gly at the level of 0.60% dThr. Collectively, we found that TDG was stimulated not only by addition of Thr and protein to the diet, but also by addition of Gly, and efficiency of Thr utilization was favorably affected by addition of Gly at the level near to the optimal Thr concentration. In addition, no metabolic requirement of Gly through the TDG pathway was observed with almost the same accumulation of Gly and a slight increase in TDG activity by addition of Gly. Thus, our findings suggest that determination of TDG activity and parameter of efficiency of Thr utilization may be useful for evaluation of dietary Thr level.

Estimation of dietary threonine requirement for growth and immune responses of broilers

This study was conducted to determine the effects of supplementing threonine (Thr) at different levels in the diets on growth performance and immune responses of broiler chickens challenged with infectious bursal disease (IBD) and also to estimate Thr requirement based on different response criterion. A total of 300 one-day-old male broiler chicks were assigned to one of the six dietary treatments. Chickens were fed eight graded levels of Thr: 0.60, 0.67, 0.74, 0.81, 0.88 or 0.95% from day 21 to 42 of age. On day 28, all birds were challenged with a commercial live-IBDV vaccine. Body weight gain (BWG), feed conversion ratio (FCR) and carcass characterisation (breast, thigh and fat pad percentage) were significantly influenced by Thr levels. Increasing advisable level up to 0.81% of the diet resulted in significant improvement in the FCR and BWG. Thr supplementation had great effects on the antibody titer against IBD; the broilers receiving the Thr levels of higher than National Research Council (NRC) recommendation have a higher IBD antibody titer than those that received lower levels of Thr. The highest (0.8224±0.0211) and the lowest (0.7240±0.0140) were estimated with straight broken-line analysis for immune response (14 days post-challenge) and breast weight, respectively. The results obtained in the present study indicated that Thr requirements of broiler based on the recommendation of NRC are not sufficient to meet the requirement of the new commercial broiler companies under stress and non-hygienic conditions. The best level of Thr based on the current study was 0.81% for support growth performance and immune function.

Supplemental glycine and threonine effects on performance, intestinal mucosa development, and nutrient utilization of growing broiler chickens

A study was conducted to evaluate Gly requirements in low-CP diets with different levels of digestible (dig) Thr, and their effects on performance, intestinal mucosal development, and nutrient utilization of broiler chickens from 21 to 35 d age. A total of 240 twenty-one-day-old Cobb-Vantress male broiler chickens were distributed in a completely randomized 4 × 2 factorial arrangement for a total of 8 treatments with 5 replicates of 6 birds each. The treatments consisted of 4 levels of Gly+Ser (1.47, 1.57, 1.67, or 1.77%) and 2 levels of dig Thr (0.70 or 0.77%, corresponding to 100 or 110% of Thr requirements, respectively). Common diets were fed to broilers until 20 d of age. At d 35, an interaction (P ≤ 0.01) was observed between the Gly+Ser and dig Thr levels for G:F. Glycine supplementation resulted in a linear increase (P < 0.05) in BW gain, G:F, intestinal mucin secretion, apparent digestibility of fat, and AME values of the experimental diets. Threonine levels greater than the levels required (0.77%) improved (P < 0.05) G:F and increased (P < 0.05) intestinal mucin secretion. However, intestinal morphometry and the number of goblet cells in the duodenum, jejunum, and ileum were not affected by the treatments. The dietary Gly+Ser level necessary to optimize G:F in low-CP diets containing 0.77% Thr for broiler chickens during growth was estimated to be 1.54%; however, this requirement may be greater than 1.77% in diets with 0.70% Thr. Supplemental Gly may be essential to support maximum performance for broiler chickens from 21 to 35 d of age when they are fed diets based exclusively on vegetable ingredients and with low protein levels. Glycine can directly or indirectly influence the proper function of the intestinal mucosa and improve dietary energy utilization.

The Effects of Amlodipine and S(-)-Amlodipine on Vascular Endothelial Function in Patients With Hypertension

Amlodipine has been shown to improve vascular endothelial function in hypertensive patients, but whether S(-)-amlodipine has a similar effect remains controversial. This study compared the effects of amlodipine and S(-)-amlodipine on vascular endothelial function in hypertensive patients and investigated relevant mechanisms of action in cell culture. Twenty-four patients with essential hypertension received amlodipine and S(-)-amlodipine for 6 weeks in a randomized, crossover study. Associated flow-mediated dilation (FMD), nitric oxide (NO), and endothelial nitric oxide synthase (eNOS) levels were determined. NO levels were measured after exposure of human umbilical vein endothelial cells (HUVECs) to amlodipine, S(-)-amlodipine, the eNOS inhibitor N w-nitro-L-arginine (L-NA), and the Protein Kinase C (PKC) inhibitor Ro 31-8220. Phosphorylation levels of Ser(1177) and Thr(495) in eNOS were determined after exposure to amlodipine, S(-)-amlodipine, and Ro 31-8220. FMD, NO, and eNOS levels significantly improved after treatment with amlodipine and S(-)-amlodipine. The levels were all higher with amlodipine, although the between-treatment difference was not statistically significant. Amlodipine and S(-)-amlodipine significantly increased NO levels in cultured HUVECs, but increases in NO levels were more marked with amlodipine. Western blot assay showed that both amlodipine and Ro31-8220 induced Ser(1177) phosphorylation and weakened Thr(495) phosphorylation in eNOS. S(-)-amlodipine had no similar effects. Amlodipine, but not S(-)-amlodipine, decreased the PKC phosphorylation in a time-dependent manner. Amlodipine and S(-)-amlodipine can both improve endothelial function in hypertensive patients. Amlodipine has greater potential for vascular endothelial protection than S(-)-amlodipine. It affects eNOS phosphorylation at Ser(1177) and Thr(495) by the PKC pathway, further enhancing eNOS activation.

Threonine Affects Intestinal Function, Protein Synthesis and Gene Expression of TOR in Jian Carp (Cyprinus carpio var. Jian)

This study aimed to investigate the effects of threonine (Thr) on the digestive and absorptive ability, proliferation and differentiation of enterocytes, and gene expression of juvenile Jian carp (Cyprinus carpio var. Jian). First, seven isonitrogenous diets containing graded levels of Thr (7.4–25.2 g/kg diet) were fed to the fishes for 60 days. Second, enterocyte proliferation and differentiation were assayed by culturing enterocytes with graded levels of Thr (0–275 mg/l) in vitro. Finally, enterocytes were cultured with 0 and 205 mg/l Thr to determine protein synthesis. The percent weight gain (PWG), specific growth rate, feed intake, feed efficiency, protein retention value, activities of trypsin, lipase and amylase, weights and protein contents of hepatopancreas and intestine, folds heights, activities of alkaline phosphatase (AKP), γ- glutamyl transpeptidase and Na+/K+-ATPase in all intestinal segments, glutamate-oxaloacetate transaminase (GOT) and glutamate-pyruvate transaminase (GPT) activities in hepatopancreas, and 4E-BP2 gene expression in muscle, hepatopancreas and intestinal segments were significantly enhanced by Thr (p<0.05). However, the plasma ammonia concentration and TOR gene expression decreased (p<0.05). In vitro, Thr supplement significantly increased cell numbers, protein content, the activities of GOT, GPT, AKP and Na+/K+-ATPase, and protein synthesis rate of enterocytes, and decreased LDH activity and ammonia content in cell medium (p<0.05). In conclusion, Thr improved growth, digestive and absorptive capacity, enterocyte proliferation and differentiation, and protein synthesis and regulated TOR and 4E-BP2 gene expression in juvenile Jian carp. The dietary Thr requirement of juvenile Jian carp was 16.25 g/kg diet (51.3 g/kg protein) based on quadratic regression analysis of PWG.

Protein and Digestible Threonine Levels in Pre Starter Diets for Broiler Chicks

This experiment was carried out in experimental poultry facilities of University of Goias to estimate digestible threonine (Thr) requirement for broiler from 1 to 21 days of age. 384 AgRoss-508 broiler chicks were allotted in a completely randomized design in a 4 x 2 factorial arrangement, with two protein levels (205 and 221 g/kg) and four digestible threonine levels (6.1, 7.1, 8.1 and 9.1 g/kg) with four replications of 12 birds each. The performance, nutrient digestibility and morfometrical index were evaluated. The polynomial regression and linear response plateau (LRP) model was used to estimate digestible, had been the Minimum Square of Deviations (MSD) utilized for choice criterion. Used polynomial regression, the results showed that a quadratic effect (p<0.05) for mean body weight at seven and 21 days of age (seven days - Y = -31.41 + 455.28x - 285.62x /21 days - Y = 510.08 + 508.91x - 324.61x ) which estimates a 7.9 and 7.1 g/kg 2 2 of digestible Thr, but LRP model showed low MSD and smaller estimates for digestible Thr levels (7.7 and 6.7 g/kg in seven and 21 days, respectively). The results showed a tendency if lower levels of digestible Thr (below to 7.1 g/kg) reduced intestinal length. The digestible Thr levels recommended for pre-starter phase vary from 7.7 at 6.7 g/kg, estimated by LRP model and 7.9 at 7.1 g/kg estimated by polynomial regression for mean body weight at seven and 21 days of age, respectively, but the LRP values presented smaller minimum square of deviations.